基于MIP试验下的煤微观结构研究和分形定量表征

Microstructure Study and Fractal Quantitative Characterization of Coal Based on MIP Test

为了解地下煤火对煤裂隙孔隙的影响,将压汞法(MIP)和分形计算相结合,研究高温处理下的煤孔隙裂隙发展的规律并计算分维数,分析煤孔隙裂隙发展与分维数之间的关系。结果表明200℃高温处理的煤样(C200)总孔体积(0.171 5 mL/g)大于400℃高温处理后的煤样(C400)总孔体积(0.120 9 mL/g),均大于原煤的0.113 5 mL/g,孔体积增加主要是中孔和大孔,C200中孔和大孔体积占比为70.15%以及C400占比59.97%。MIP分维数随温度的升高呈现降低的趋势,温度越高煤样贯通性越好,C200和C400孔体积和三维分维数的变化呈现相反的趋势与煤基质在不同温度下受力不同有关。温度越高分维数越小,裂隙孔隙的贯通程度越好,煤的内部微观结构不同尺寸的分布相对均匀。

In order to understand the influence on coal fracture pores from underground coal fire,mercury intrusion pressure method(MIP)and fractal calculation were combined to study the law of coal pore fracture development under high temperature treatment,calculate the dimensional fraction,and analyze the relationship between coal pore fracture development and dimensional composition.The results shows that the total pore volume(0.1715mL/g)of coal samples treated at 200°C was greater than that of coal samples treated at 400°C(0.1209mL/g),which is greater than 0.1135mL/g of raw coal,and the volume increase was mainly due to mesoporous and macroporous volumes,with the proportion of mesoporous and macroporous volumes in C200 being 70.15%and C400 accounting for 59.97%.The MIP dimension decreases with the increase of temperature,the higher the temperature,the better the penetration of coal samples,and the changes of volume and three-dimensional dimension of C200 and C400 show opposite trends,which is related to the different forces of coal matrix at different temperatures.The higher the temperature,the smaller the dimension,the better the penetration of fracture pores,and the distribution of different sizes of the internal microstructure of coal is relatively uniform.